Oil residue carbon dots, preparation method and application in detection of mercury ions and chlortetracycline hydrochloride

Abstract

The invention discloses an oil residue carbon dot, a preparation method and application in detection of mercury ions and chlortetracycline hydrochloride, and belongs to the technical field of fluorescent nanomaterials, the carbon dot is an oil residue carbon dot ROR-CDs, oil residue and citric acid are used as raw materials, and the carbon dot ROR-CDs with blue fluorescence emission is prepared through a self-propagating pyrolysis method. Fluorescence detection tests on different heavy metal ions and different antibiotics find that the carbon quantum dots synthesized by the method can detect trace mercury ions and chlortetracycline hydrochloride in a pure water medium with high sensitivity and high selectivity; by means of specific binding of carbon quantum dot heteroatom functionalized surface groups with mercury ions and chlortetracycline hydrochloride, interference of other coexisting substances in the detection process can be reduced, and the probe has potential application prospects in the field of detection of harmful pollutants in water and other environments.

Description

Technical Field

[0001] The invention belongs to the technical field of fluorescent nanomaterials, and specifically relates to an oil residue carbon dot, a preparation method and an application in detecting mercury ions and chlortetracycline hydrochloride. Background Art

[0002] Heavy metal pollution is a great threat to human health and environmental protection and has attracted much attention. 2+ Hg is the most common pollutant in environmental water. It is bioaccumulative and highly toxic, and can cause serious damage to human health. Therefore, the development of the detection of trace Hg 2+ Currently, the method used for Hg 2+ The main detection methods include atomic absorption / emission spectroscopy, X-ray absorption spectroscopy, inductively coupled plasma mass spectrometry, and ion chromatography. However, most of these methods require expensive precision equipment and professionals, and require complex sample pretreatment. Fluorescence analysis is popular because of its simplicity, high efficiency, and sensitivity. Therefore, it is necessary to establish a convenient and rapid detection method for Hg 2+ The analysis method is of great significance.

[0003] Chlortetracycline hydrochloride (CTC) is a tetracycline antibiotic with good antibacterial effect and low price. It is widely used as veterinary drugs and feed additives in animal husbandry. However, most CTCs are not absorbed and metabolized by animals, but are excreted with animal excrement, which pollutes land and water sources to a certain extent. Its residues will eventually enter the human body through the food chain, leading to various human diseases such as aplastic anemia and myeloid leukemia. Therefore, it is very necessary to detect CTCs. At present, the methods for detecting CTCs include liquid chromatography tandem mass spectrometry (LC-MS), microbiological method, enzyme-linked immunosorbent assay (ELISA) and high-performance liquid chromatography (HPLC). These methods have high sensitivity and accuracy. However, LC-MS and HPLC methods require expensive instruments and equipment and complex sample pretreatment; ELISA method is easily affected by temperature and time; microbiological method is difficult to quantify. Therefore, a simpler and faster method for detecting CTC content should be developed.

[0004] Carbon dots (CDs) are a new type of luminescent carbon nanomaterial with a diameter of less than 10nm. Due to its excellent optical properties, good chemical stability, green preparation method, low cost and excellent biocompatibility, it is widely used in analytical sensing, environmental monitoring, photoelectric sensing and bioimaging, as well as fluorescent probes. According to different heteroatom doping methods for synthesizing carbon dots, the main components of carbon dots include S, P and B in addition to C, H, O and N elements. Different synthesis methods and characterization sample preparation methods will lead to different carbonization degrees of carbon dots, thus affecting the morphology of carbon dots. TEM can be used to observe the different morphological characteristics of the carbon core of carbon dots. Summary of the invention

[0005] A kind of oil residue carbon dots, preparation method and application in detecting mercuric ions and chlortetracycline hydrochloride. The synthesized carbon dots can detect trace mercuric ions and chlortetracycline hydrochloride with high sensitivity and high selectivity in pure water medium. The surface groups functionalized with heteroatoms of carbon dots are used to specifically bind with mercuric ions and chlortetracycline hydrochloride, which can reduce the interference of other coexisting substances in the detection process. The specific contents are as follows:

[0006] An oil residue carbon dot, wherein the oil residue carbon dot is ROR-CDs, and the preparation method of the oil residue carbon dot comprises:

[0007] Step 1, drying the oil residue material, and crushing the dried oil residue into 100-mesh oil residue powder;

[0008] Step 2, preparing a mixed solvent, mixing water and saturated potassium nitrate solution in a volume ratio of 1:1 to form solvent A;

[0009] Step 3, the oil residue powder in step 1 and citric acid are sampled in a mass ratio of 2:1 and mixed to obtain solute B, and 3 g of solute B is dissolved in 20 mL of solvent A to obtain a mixed solution;

[0010] Step 4, putting the mixed solution prepared in step 3 into an oven to dry to obtain a solid;

[0011] Step 5: Grind the dried solid into powder and pour it into a heating plate to initiate a combustion reaction. Cool it naturally to room temperature and collect the powder into a beaker.

[0012] Step six, dissolving the powder collected in step five in water, filtering to obtain a solution, evaporating the solution to dryness, and obtaining oil residue carbon dots ROR-CDs with blue fluorescence emission.

[0013] Furthermore, the heating conditions for initiating the combustion reaction in step five are a temperature of 1000° C. and a dwell time of 20 minutes.

[0014] Application of oil residue carbon dots in detection of mercury ions and chlortetracycline hydrochloride.

[0015] Furthermore, the ROR-CDs are used as fluorescent probes to detect mercury ions Hg 2+ .

[0016] Furthermore, the ROR-CDs detects mercury ions Hg 2+ The steps include:

[0017] 1) Dissolving the oil residue carbon dots in water to obtain ROR-CDs solution;

[0018] 2) Hg 2+ The solution was mixed with the ROR-CDs solution and different volumes of 1 mM Hg 2+ solution, dilute to 1.0 mL with pH 8 phosphate buffer solution to form Hg 2 Concentration gradient, λEm is measured at different concentrations of Hg at 350nm 2+ The fluorescence intensity of the solution, F0, was obtained;

[0019] 3) Mixing the sample to be tested with the ROR-CDs solution under the condition of pH=8.0 to obtain a mixed solution of the sample to be tested, and measuring the fluorescence intensity F of the mixed solution of the sample to be tested;

[0020] 4) According to the fluorescence quenching efficiency F / F0 and Hg 2+ The linear relationship between the concentration and the Hg content in the sample to be tested is calculated. 2+ concentration;

[0021] The linear relationship is obtained by obtaining the fluorescence quenching efficiency F / F0 and Hg 2+ Linear relationship with concentration.

[0022] Furthermore, the fluorescence quenching efficiency F / F0 and Hg 2+ The linear relationship of concentration includes:

[0023] In the range of 0-20 μg / L, the linear equation is y=0.97453-0.01565*x; R 2 =0.9926, LOD=19.16ng / L;

[0024] In the range of 20-250 μg / L fluorescence, the linear equation is y=0.64582-0.00165*x; R 2 =0.9910, LOD=18.18ng / L.

[0025] Furthermore, the ROR-CDs are used as fluorescent probes to quickly detect the CTC content of chlortetracycline hydrochloride.

[0026] Furthermore, the step of detecting chlortetracycline hydrochloride by ROR-CDs comprises:

[0027] 1) Dissolving the oil residue carbon dots in water to obtain ROR-CDs solution;

[0028] 2) Mix the chlortetracycline hydrochloride CTC to be detected with 10 μL ROR-CDs solution, add different volumes of 1 mM CTC solution, and dilute to 1.0 mL with pH=12 phosphate buffer solution to form a CTC concentration gradient. Measure the fluorescence intensity of CTC solutions of different concentrations at λEm of 350 nm to obtain F0;

[0029] 3) Mixing the sample to be tested with the ROR-CDs solution under the condition of pH=12.0 to obtain a mixed solution of the sample to be tested, and measuring the fluorescence intensity F of the mixed solution of the sample to be tested;

[0030] 4) Calculate the concentration of CTC in the sample to be tested based on the linear relationship between the fluorescence quenching efficiency F / F0 and the CTC concentration.

[0031] Furthermore, the linear relationship between the fluorescence quenching efficiency F / F0 and the CTC concentration is used to calculate the concentration of CTC in the sample to be tested, including:

[0032] When the fluorescence linear range is 0-5 μM, the linear equation is y=0.19174+0.23463*x; R 2 =0.9938; detection limit is 12.7nM (S / N=3);

[0033] When the fluorescence linear range is 5-50 μM, the linear equation is y=0.96032+0.08678*x; R 2 =0.9939; detection limit is 34.57nM (S / N=3).

[0034] Working mechanism of the present invention: The present invention adopts a self-propagating pyrolysis method to prepare oil residue carbon dots ROR-CDs, uses waste biomass oil residue as raw material, fully utilizes the principle of self-propagating pyrolysis, does not rely on other additional energy, and based on the catalytic action of nitrate and biomass in the form of a self-propagating combustion wave, an exothermic redox reaction occurs, forming ROR-CDs in a relatively short time, and is used as a fluorescent probe for analyzing and detecting mercury ions and chlortetracycline hydrochloride.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] (1) After consulting a large amount of information, it is found that there is no relevant literature report on the self-propagating pyrolysis method for preparing carbon dots. The present invention adopts the self-propagating pyrolysis method, which involves a simple and efficient process, low cost, forms biochar in a relatively short time, and the prepared carbon dots are relatively pure, without the need for subsequent separation and purification.

[0037] (2) Using waste biomass oil residue as raw material realizes the recycling of resources and green production.

[0038] (3) Preparation of new carbon dots for Hg detection 2+ It has good detection effect and high sensitivity for CTC. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 TEM image and particle size distribution diagram of ROR-CDs;

[0040] Figure 2 is the XRD pattern of ROR-CDs;

[0041] Figure 3 is the X-ray photoelectron spectroscopy (XPS) spectrum of ROR-CDs, where:

[0042] (a) Full XPS spectrum of ROR-CDs;

[0043] (b) is the C1s spectrum;

[0044] (c) is the N1s spectrum;

[0045] (d) is the O1s spectrum;

[0046] Figure 4 FTIR images of ROR and ROR-CDs;

[0047] Figure 5 UV-Vis, excitation and emission spectra of ROR-CDs;

[0048] Figure 6 The fluorescence emission spectra and full wavelength diagram of ROR-CDs under different excitations;

[0049] Figure 7 is the fluorescence lifetime decay curve of ROR-CDs;

[0050] Figure 8 The results of characterization of the stability of ROR-CDs are shown in Figure 2.

[0051] (a) Effect of pH on the emission peak value,

[0052] (b) Effect of NaCl concentration on the emission peak.

[0053] (c) Effect of H2O2 concentration on the emission peak.

[0054] (d) The effect of natural light on the peak emission value,

[0055] (e) The effect of UV light on the peak emission value;

[0056] Fig. 9 ROR-CDs as a fluorescent probe for the detection of Hg 2+ The condition optimization results are:

[0057] (a) Effect of pH on Hg detection by ROR-CDs 2+ Fluorescence value changes affect

[0058] (b) Effect of reaction time on Hg detection by ROR-CDs 2+ Fluorescence value changes;

[0059] Fig.10 Detection of Hg for ROR-CDs 2+ Interference performance study results;

[0060] Fig.11 Detection of Hg for ROR-CDs 2+ The results of the analysis results;

[0061] (a) Fluorescence value change and Hg 2+ Linear fitting of concentration (0~250μg / L),

[0062] (b)Hg 2+ Fluorescence spectra of quenched ROR-CDs;

[0063] Fig.12 ROR-CDs+Hg 2+ The results of the fluorescence quenching mechanism study,

[0064] (a) ROR-CDs, Hg 2+ , ROR-CDs and Hg 2+ The UV absorption spectrum of the mixture,

[0065] (b) Fluorescence spectra of ROR-CDs and Hg 2+ The absorption spectrum of

[0066] (c)ROR-CDs, ROR-CDs+Hg 2+ FL decay lifetime diagram,

[0067] (d) Hg at different temperatures 2+ Stern-Volmer equation for fluorescence quenching of ROR-CDs;

[0068] Fig.13 The results of the optimization of the conditions for using ROR-CDs as a fluorescent probe to analyze and detect CTCs.

[0069] (a) Effect of pH value on the fluorescence value of CTC detected by ROR-CDs.

[0070] (b) Effect of reaction time on the change of CTC fluorescence value detected by ROR-CDs

[0071] Fig.14 Study on the interference performance of ROR-CDs in detecting CTCs;

[0072] Fig.15 The results of the ROR-CDs detection of CTCs were analyzed.

[0073] (a) Linear fitting of the fluorescence value change from 0 to 50 μM and the CTC concentration,

[0074] (b) Fluorescence spectrum of CTC-sensitized CDs. DETAILED DESCRIPTION

[0075] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings. It should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present invention. In addition, in the following invention, the description of well-known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present invention.

[0076] Example 1: Preparation of oil residue carbon dots ROR-CDs

[0077] The oil residue is placed in an oven to dry, and after drying, it is crushed to 100 meshes to obtain oil residue powder.

[0078] Weigh 10g of oil residue powder and 5g of citric acid into a beaker, add 50mL of water and 50ml of saturated potassium nitrate solution, stir evenly with a glass rod, and then put the beaker into an oven to dry. After drying, pour out the solid, put it into a mortar and grind it into powder, pour it onto a heating plate, turn the beaker upside down on it, adjust the temperature to 1000℃, stay for 20 minutes to induce a combustion reaction, cool naturally to room temperature, collect the powder into a beaker, add water to dissolve it, filter to obtain a solution, evaporate the solution to dryness, and obtain oil residue carbon dots ROR-CDs, which show obvious blue fluorescence under ultraviolet light.

[0079] Example 2: Structural Characterization of ROR-CDs Prepared in Example 1

[0080] The prepared ROR-CDs were structurally characterized using TEM, XRD, XPS and FTIR.

[0081] (1) Transmission electron microscopy (TEM)

[0082] Transmission electron microscopy (TEM): observe the morphology and particle size distribution of ROR-CDs, and calculate the average particle size using the statistical average method. Figure 1 As shown, ROR-CDs are spherical as a whole, without obvious aggregation. The average particle size of the carbon dots was about 2.98 nm as plotted using Nano Measure software and Origin software.

[0083] (2) X-ray powder diffraction pattern (XRD):

[0084] The crystallinity of CDs was studied by XRD. Since saturated potassium nitrate solution was added to prepare CDs, potassium ions were present. Figure 2 As shown, the XRD pattern of ROR-CDs has a broad peak at 2θ of 30.90°.

[0085] (3) X-ray photoelectron spectroscopy (XPS): Qualitative and semi-quantitative analysis of ROR-CDs was performed to obtain information on the surface element composition and chemical state of ROR-CDs. The results are as follows: Figure 3 As shown in a, the four peaks at 168.88 eV, 284.99 eV, 407.08 eV and 532.16 eV are attributed to the characteristic absorption peaks of S2p spectrum, C1s spectrum, N1s spectrum and O1s spectrum, respectively.

[0086] There are four peaks in the C1s spectrum: 284.75 eV corresponds to CC, 287.93 eV corresponds to CN / COC, and 292.59 eV corresponds to -COOH ( Figure 3 b); Figure 3 c shows that the N1s spectrum has two obvious peaks at 400.47eV (NH) and 407.19eV (Graphitic N); the two peaks of the O1s spectrum appear at 531.88eV and 532.88eV, corresponding to CO / -OH and OH, respectively. Figure 3 d).

[0087] (4) Fourier transform infrared spectroscopy (FTIR): It can be used to infer the surface chemical groups and chemical composition of carbon dots and to identify the structures of unknown compounds.

[0088] The results are as follows Figure 4 As shown, ROR-CDs has a strong absorption peak at 3442.85 cm-1, indicating the existence of OH and CH bonds, indicating that ROR-CDs have OH and CH groups; a peak at 2928.16 cm-1 indicates the existence of a CH bond; a peak at 1654.88 cm-1 indicates the existence of a C=C bond; an obvious peak appears at 1059.71 cm-1, indicating the existence of a CO bond in ROR-CDs.

[0089] Example 3: Characterization of optical properties of ROR-CDs prepared in Example 1

[0090] (1) Ultraviolet-visible absorption spectrum (UV-Vis)

[0091] Using ultraviolet spectrophotometry and distilled water as blank control, the ultraviolet absorption characteristic spectrum and absorbance of ROR-CDs were analyzed and determined to understand the surface transition and conjugation of ROR-CDs.

[0092] The UV-visible absorption peaks of ROR-CDs are as follows: Figure 5 As shown in Figure 2, ROR-CDs have an obvious absorption peak at 237 nm, which is due to the sp 2 Hybridization leads to π→π* transition. The fluorescence spectra of ROR-CDs at different excitation wavelengths were measured by fluorescence spectrophotometer ( Figure 5 ), indicating that its optimal excitation spectrum (Ex) and emission spectrum (Em) are located at 350nm and 450nm, respectively. Figure 5 The illustration is a color comparison of the ROR-CDs solution under ultraviolet light and natural light, indicating that the carbon dots can emit strong blue fluorescence under ultraviolet light (365nm).

[0093] (2) Fluorescence quantum yield (QY)

[0094] Calculate the relative fluorescence quantum yield. Quinine sulfate was dissolved in 0.1M H2SO4 solution, and its fluorescence quantum yield at 360nm was 0.54, which was used as the standard for the determination and calculation of the fluorescence intensity value and UV-visible absorbance value of ROR-CDs and quinine sulfate. By adjusting the concentration of the solution, the absorbance was lower than 0.1 to reduce the influence of reabsorption. The quantum yield calculation formula is:

[0095] QY=Q R (I S / I R )(A R / A S )(η S 2 / η R 2 )

[0096] Q R —Theoretical quantum yield of quinine sulfate;

[0097] η S — the refractive index of water;

[0098] η R —The refractive index of 0.1M H2SO4.

[0099] The results are as follows: At an excitation wavelength of 360 nm, the quantum yield (QR) of the standard fluorescent substance quinine sulfate is 0.54, and the refractive index (η S , η R ) were all 1.33, and the fluorescence quantum yield of the prepared ROR-CDs was 8.28%.

[0100] (4) Fluorescence lifetime

[0101] The fluorescence lifetime of ROR-CDs solution at Em of 450 nm was determined by time-correlated single photon counting (TCSPC) to be 3.85 ns (e.g. Figure 7 ).

[0102] Example 4: Characterization of the stability of ROR-CDs prepared in Example 1

[0103] (1) pH stability: 10 μL of ROR-CDs solution was placed in a centrifuge tube, and then phosphate buffer solution (pH 2.2-12) was taken to make up to 1.0 mL. The tube was then vortexed for 2 min on a vortexer. The fluorescence intensity of ROR-CDs was then measured at an excitation wavelength of 350 nm. The excitation and emission slit widths were 2.5 nm and 2.5 nm, respectively.

[0104] The results are as follows Figure 8 As shown in a, the fluorescence value increases in the pH range of 2.2 to 4, decreases in the pH range of 4 to 5, and increases in the pH range of 5 to 8. It is relatively stable in the pH range of 8 to 12. Under alkaline conditions, ROR-CDs have higher fluorescence values ​​and are relatively stable.

[0105] (2) Ionic strength stability: Take 10 μL ROR-CDs solution in a centrifuge tube, then take different volumes of 2 M NaCl solution, and then dilute to 1.0 mL with ultrapure water. Determine the fluorescence intensity value; the fluorescence detection method is the same as above.

[0106] The results are as follows Figure 8 As shown in b, when the NaCl concentration is 0.4-2.0 M, the fluorescence intensity of ROR-CDs remains basically unchanged, indicating that ROR-CDs has a certain salt tolerance.

[0107] (3) Antioxidant activity: Take 10 μL ROR-CDs solution in a centrifuge tube, then take different volumes of 0.5 M H2O2 solution, and then make up to 1.0 mL with ultrapure water. Determine the fluorescence intensity value, and the fluorescence detection method is the same as above.

[0108] The results are as follows Figure 8 As shown in Figure c, at concentrations of 0 to 0.04 M, the fluorescence intensity decreased significantly and then tended to be flat, but overall the fluctuation was small, indicating that ROR-CDs have relatively stable antioxidant properties.

[0109] (4) Photobleaching resistance: Take 10 μL of ROR-CDs solution in a centrifuge tube, dilute to 1.0 mL with ultrapure water, shake well, and irradiate with natural light / ultraviolet light (wavelength of 365 nm) and measure the fluorescence intensity value; the fluorescence detection method is the same as above.

[0110] The results are as follows Figure 8 As shown in Figures 8d and 8e, the fluorescence intensity of CDs remained basically stable within 60 minutes under natural light; the fluorescence intensity of CDs remained basically stable within 60 minutes under continuous irradiation with an ultraviolet light box (wavelength of 365 nm), indicating that ROR-CDs have good anti-photobleaching ability.

[0111] Example 5: ROR-CDs as a fluorescent probe for the analysis and detection of Hg 2+

[0112] (1) Effect of pH value on fluorescence response:

[0113] Take 10 μL of ROR-CDs solution in a centrifuge tube and add 30 μL of 1 mM Hg 2+ For the standard solution, dilute to 1.0 mL with phosphate buffer of different pH values ​​(2.2-12.0), vortex and mix for 4 min. Set the excitation and emission slit widths to 2.5 nm and 2.5 nm, respectively, and measure the fluorescence values ​​of different pH values ​​at an excitation wavelength of 350 nm. Select the optimal pH.

[0114] Results from Fig. 9 a It can be seen that the fluorescence intensity increases with the increase of pH value and is relatively stable when the pH is 8-12.

[0115] (2) Impact of reaction time

[0116] Take 10 μL of ROR-CDs solution in a centrifuge tube and use pH 8 (ROR-CDs detection Hg 2+ The optimal pH of the phosphate buffer solution was diluted to 1.0 mL. The excitation and emission slit widths were set to 2.5 nm and 2.5 nm respectively, and a blank value F0 was measured at an excitation wavelength of 350 nm. 1 mM Hg 30 μL was added to the same solution. 2+ The solution was added and the fluorescence intensity of ROR-CDs was immediately measured to select the optimal reaction time.

[0117] Results from Fig. 9 b It can be seen that the reaction is in a stable state after 4 minutes.

[0118] (3) Selectivity

[0119] Take 10 μL of ROR-CDs solution and place it in a centrifuge tube, then add 100 μL of 1 mM metal ion (Hg 2+ 、As 6+ , Pb 2+ , Fe 3+ Cr 6+ 、Ag + , Cu 2+、Cd 2+ , Ba 2+ 、Zn 2+ , Mn 2+ 、Na + , K + , Ca 2+ Mg 2+ ), anion (F + , Cl - Br - ,I - 、NO 3- 、SO4 2- PO4 3- 、CO3 2- ), vitamins (VC, VB1) were added to the above solution, and the volume was adjusted to 1.0 mL with a phosphate buffer solution of pH 8. After vortexing for 4 minutes, the excitation and emission slit widths were set to 2.5 nm and 2.5 nm respectively, and the fluorescence value of ROR-CDs was measured at an excitation wavelength of 350 nm. 2+ anti-interference ability.

[0120] The results are as follows Fig.10 Hg 2+ When Hg is present, the fluorescence value F / F0 is significantly reduced, while other metal ions, anions, and vitamins (VB1, VC) have little effect on the fluorescence intensity of ROR-CDs, which indicates that ROR-CDs are suitable for detecting Hg as a fluorescent probe. 2+ Has good selectivity.

[0121] (4) Methodological research

[0122] Take 10 μL of ROR-CDs solution and place it in a centrifuge tube. Add different volumes of 1 mM Hg 2+ solution, and dilute to 1.0 mL with pH 8 phosphate buffer solution to form Hg 2+ The concentration gradient was vortexed for 4 minutes. The excitation and emission slit widths were set to 2.5 nm and 2.5 nm respectively. The fluorescence intensity of ROR-CDs was measured at 350 nm as the optimal excitation wavelength and a standard curve was drawn. F / F0 was the vertical coordinate Hg 2+ The concentration is taken as the horizontal axis, and its equation, correlation coefficient and detection limit are calculated after linear fitting.

[0123] The results are as follows Fig.11 As shown, the fluorescence value F / F0 and Hg 2+The concentration of ROR-CDs showed a good linear relationship. When the fluorescence linear range was 0-20 μg / L, the linear equation was y=0.97453-0.01565*x; R2=0.9926, LOD=19.16 ng / L. When the fluorescence linear range was 20-250 μg / L, the linear equation was y=0.64582-0.00165*x; R2=0.9910, LOD=18.18 ng / L. It can be seen that ROR-CDs can be used as a fluorescent sensor to detect Hg 2+ The content.

[0124] Consult relevant literature reports and compare the detection of Hg in this experiment 2+ The fluorescence analysis method is compared with other methods.

[0125] Table 1 Detection of Hg 2+ Comparison of methods

[0126]

[0127] As shown in Table 1, compared with the existing carbon dots detection of Hg 2+ The ROR-CDs detection range of the present invention is wider.

[0128] (5) Fluorescence quenching mechanism study

[0129] like Fig.12 As shown in a: fluorescence quenching reaction occurs, ROR-CDs+Hg 2+ No new UV absorption peaks appeared. ROR-CDs fluorescence spectrum and Hg 2+ The ultraviolet absorption superposition of Fig.12 b, Excitation and emission bands of ROR-CDs fluorescence spectra and Hg 2+ The UV absorption peaks of ROR-CDs and Hg 2+ The fluorescence decay lifetimes at different concentrations are 4.00, 3.84, 3.80, and 3.77 ns, respectively, and the fluorescence lifetime of ROR-CDs remains basically unchanged ( Fig.12 c), therefore, Hg 2+ The quenching mechanism may be SQ. The Stern-Volmer equation is used to further verify:

[0130] F0 / F=1+K SV [c]=1+Kqτ0[c]

[0131] K SV is the dynamic quenching constant, Kq is the dynamic quenching rate constant, τ0 is the average lifetime of the phosphor, and 1-(F / F0) is plotted against [c] at 288K, 298K and 310K.

[0132] The results are as follows Fig.12 d is Hg at different temperatures 2+ The Stern-Volmer curve of ROR-CDs fluorescence quenching shows that at three different temperatures, as the temperature increases, the slope K SV Also decreases, so this process belongs to static quenching (SQ)

[0133] In summary, ROR-CDs were used as fluorescent probes to detect Hg 2+ The optimal pH for detection is 8, and the optimal reaction time is 5 min. It is used to detect Hg 2+ Has good selectivity. Fluorescence value F / F0 and Hg 2+ The concentration showed a good linear relationship. When the fluorescence linear range was 0-20 μg / L, the linear equation was y=0.97453-0.01565*x; R 2 =0.9926, LOD = 19.16 ng / L. When the fluorescence linear range is 20-250 μg / L, the linear equation is y = 0.64582-0.00165*x; R 2 =0.9910, LOD = 18.18 ng / L. It can be seen that ROR-CDs can be used as a fluorescent probe to detect Hg 2+ The content.

[0134] Hg 2+ Fluorescence quenching mechanism of ROR-CDs, ROR-CDs+Hg 2+ No new UV absorption peaks appeared, and the excitation and emission bands of the fluorescence spectrum of ROR-CDs were similar to those of Hg 2+ The UV absorption peaks of Hg 2+ The concentration of Hg decreases with the increase of the concentration. The Stern-Volmer equation verifies that this process belongs to static quenching (SQ). 2+ The fluorescence quenching mechanism is SQ.

[0135] Example 6: ROR-CDs as a fluorescent probe for detecting chlortetracycline hydrochloride (CTC)

[0136] The oil residue carbon dots ROR-CDs prepared in Example 1 were dissolved in an aqueous solution to prepare a ROR-CDs solution.

[0137] (1) Effect of pH value on fluorescence response:

[0138] Take 10 μL of ROR-CDs solution in a centrifuge tube, add 30 μL of 1 mM CTC standard solution, and then dilute to 1.0 mL with phosphate buffer of different pH values ​​(2.2-12.0), vortex and react for 5 minutes. Measure the fluorescence values ​​of different pH values ​​at an excitation wavelength of 350 nm and select the optimal pH.

[0139] Results from Fig.13 It can be seen from a that the fluorescence intensity increases with the increase of pH value. This is because after adding CTC, as the pH increases, the protonation of CTC in the solution increases, causing its fluorescence intensity to increase.

[0140] (2) Impact of response time

[0141] Take 10μL ROR-CDs solution in a centrifuge tube and dilute to 1.0mL with phosphate buffer solution of pH 12 (optimal pH for ROR-CDs to detect CTC). Set the excitation and emission slit widths to 2.5nm and 2.5nm respectively, and measure a blank value at an excitation wavelength of 350nm. Add 30μL of 1mM CTC solution to the solution, measure the fluorescence value every one minute for 15min, and select the best response time.

[0142] Results from Fig.13 b It can be seen that the reaction is in a stable state after 13 minutes.

[0143] (3) Selectivity

[0144] The effect of antibiotics on the use of fluorescent probes to detect CTCs was investigated. Take 10 μL of ROR-CDs solution in a centrifuge tube. Then add 100 μL, 1 mM of different antibiotics (CTC, GEN, CLX, CES, FO, CTX, CEZ, SH, KAN, EM, OTC, TC, SPX, CEC, MTZ, RAD, CXM, CIP, ENC, CAZ, AZM, C) and vitamins (VC, VB1, VE) to the above solution, dilute to 1.0 mL with pH 12 phosphate buffer solution, vortex mix for 2 minutes, set the excitation and emission slit widths to 2.5 nm and 2.5 nm respectively, and measure the fluorescence value of ROR-CDs at an excitation wavelength of 350 nm. The anti-interference ability of ROR-CDs in detecting CTCs was judged based on the fluorescence value.

[0145] Results from Fig.14 As shown: When CTC is present, the fluorescence value F0 / F is significantly reduced, while other antibiotics basically have no effect on the fluorescence intensity value of ROR-CDs, which indicates that ROR-CDs has good selectivity for detecting CTC as a fluorescent probe.

[0146] (4) Methodological research

[0147] Take 10 μL of ROR-CDs solution in a centrifuge tube, add different volumes of 1 mM CTC solution, and dilute to 1.0 mL with a phosphate buffer solution of pH 12 to form a CTC concentration gradient, and vortex mix for 2 minutes. Set the excitation and emission slit widths to 2.5 nm and 2.5 nm, respectively, and measure the fluorescence intensity of ROR-CDs at 350 nm as the optimal excitation wavelength and draw a standard curve, with F / F0 as the ordinate and the concentration of CTC as the abscissa. After linear fitting, calculate its equation, correlation coefficient, and detection limit range.

[0148] Results from Fig.15 As shown in the figure, when the fluorescence linear range is 0-5 μM, the fluorescence value F / F0 and the concentration of CTC show a good linear relationship, and the linear equation is y=0.19174+0.23463*x; R 2 =0.9938; the detection limit is 12.7nM (S / N=3). When the fluorescence linear range is 5-50μM, the fluorescence value F / F0 and the concentration of CTC show a good linear relationship, and the linear equation is y=0.96032+0.08678*x; R 2 =0.9939; the detection limit is 34.57 nM (S / N=3). It can be seen that ROR-CDs can be used as a fluorescent sensor to detect the content of CTC.

[0149] The fluorescence analysis method for detecting CTCs was compared with other methods, as shown in Table 2.

[0150] Table 2 Comparison of methods for detecting chlortetracycline hydrochloride

[0151]

[0152] The results shown in Table 2 show that ROR-CDs are used as fluorescent probes to detect CTCs, which is more sensitive than existing carbon dot detection methods.

[0153] In summary, ROR-CDs was used as a fluorescent probe to detect chlortetracycline hydrochloride (CTC), with the optimal pH of 12 and the optimal reaction time of 13 min, and had good selectivity for detecting CTC. When the fluorescence linear range was 0-5 μM, the fluorescence value F / F0 showed a good linear relationship with the concentration of CTC, and the linear equation was y=0.19174+0.23463*x; R 2 =0.9938; the detection limit is 12.7nM (S / N=3). When the fluorescence linear range is 5-50μM, the fluorescence value F / F0 and the concentration of CTC show a good linear relationship, and the linear equation is y=0.96032+0.08678*x; R 2=0.9939; the detection limit is 34.57 nM (S / N=3). It can be seen that ROR-CDs can be used as a fluorescent probe to detect the content of CTC.

[0154] According to Examples 1-6, (1) ROR-CDs with blue fluorescence emission carbon dots were prepared by self-propagating pyrolysis using oil residue and citric acid as raw materials, and the structure and optical properties of the prepared ROR-CDs were characterized. The particle size of ROR-CDs was 2.98 nm, the optimal excitation and emission wavelengths were 350 nm and 450 nm, respectively, the average fluorescence lifetime at 450 nm was 3.85 ns, and the quantum yield was 8.28%. The prepared ROR-CDs are not acid-resistant, but are relatively stable under alkaline conditions, and have good antioxidant, salt resistance, and anti-photobleaching stability.

[0155] (2) ROR-CDs as a fluorescent probe for Hg analysis 2+ Through condition optimization, selectivity investigation and detection methodology, ROR-CDs were used as fluorescent probes to detect Hg 2+ The optimal pH for detection is 8, the optimal reaction time is 4 min, and ROR-CDs detects Hg 2+ Has good selectivity. Fluorescence value F / F0 and Hg 2+ The concentration of ROR-CDs showed a good linear relationship. When the fluorescence linear range was 0-20 μg / L, the linear equation was y=0.97453-0.01565*x; R2=0.9926, LOD=19.16 ng / L. When the fluorescence linear range was 20-250 μg / L, the linear equation was y=0.64582-0.00165*x; R2=0.9910, LOD=18.18 ng / L. It can be seen that ROR-CDs can be used as a fluorescent probe to detect Hg 2+ The content.

[0156] Study on Hg 2+ Quenching mechanism of ROR-CDs fluorescence, ROR-CDs+Hg 2+ No new UV absorption peaks appeared, and the excitation and emission bands of the fluorescence spectrum of ROR-CDs were similar to those of Hg 2+ The UV absorption peaks of Hg 2+ The concentration decreased with increasing, which was further verified by the Stern-Volmer equation, and the process belonged to static quenching (SQ).

[0157] (3) ROR-CDs was used as a fluorescent probe to detect chlortetracycline hydrochloride (CTC). The optimal pH for detection was 12, and the optimal reaction time was 13 min. It had good selectivity for detecting CTC. When the fluorescence linear range was 0-5 μM, the fluorescence value F / F0 showed a good linear relationship with the concentration of CTC, and the linear equation was y=0.19174+0.23463*x; R 2 =0.9938; detection limit is 12.7nM (S / N=3). When the fluorescence linear range is 5-50μM, the linear equation is y=0.96032+0.08678*x; R 2 =0.9939; the detection limit is 34.57 nM (S / N=3). It can be seen that ROR-CDs can be used as a fluorescent probe to detect the content of CTC.

[0158] It should be understood that the above specific embodiments of the present invention are only used for illustrative inventions or to explain the principles of the present invention, and do not constitute limitations on the present invention. Therefore, any modifications, equivalent substitutions, improvements, etc. made without departing from the spirit and scope of the present invention should be included in the protection scope of the present invention. In addition, the appended claims of the present invention are intended to cover all changes and modifications that fall within the scope and boundaries of the appended claims, or the equivalent forms of such scope and boundaries.

Claims

1. An oil residue carbon dot, characterized in that: The oil residue carbon dots are ROR-CDs, and the preparation method of the oil residue carbon dots comprises: Step 1, drying the oil residue material, and crushing the dried oil residue into 100-mesh oil residue powder; Step 2, preparing a mixed solvent, mixing water and saturated potassium nitrate solution in a volume ratio of 1:1 to form solvent A; Step 3, the oil residue powder in step 1 and citric acid are sampled in a mass ratio of 2:1 and mixed to obtain solute B, and 3 g of solute B is dissolved in 20 mL of solvent A to obtain a mixed solution; Step 4, putting the mixed solution prepared in step 3 into an oven to dry to obtain a solid; Step 5: Grind the dried solid into powder and pour it into a heating plate to initiate a combustion reaction. Cool it naturally to room temperature and collect the powder into a beaker. Step six, dissolving the powder collected in step five in water, filtering to obtain a solution, evaporating the solution to dryness, and obtaining oil residue carbon dots ROR-CDs with blue fluorescence emission.

2. The oil residue carbon dots according to claim 1, characterized in that: The heating condition for initiating the combustion reaction in step 5 is a temperature of 1000° C. and a dwell time of 20 minutes.

3. An application of the oil residue carbon dots according to claim 1 or 2 in detecting mercury ions and chlortetracycline hydrochloride.

4. The use according to claim 3, characterized in that: The ROR-CDs are used as fluorescent probes to detect mercury ions Hg 2+ .

5. The application according to claim 4, characterized in that: The ROR-CDs detect mercury ions Hg 2+ The steps include: 1) Dissolving the oil residue carbon dots in water to obtain ROR-CDs solution; 2) Hg 2+ The solution was mixed with the ROR-CDs solution and different volumes of 1 mM Hg 2+ solution, dilute to 1.0 mL with pH 8 phosphate buffer solution to form Hg 2 Concentration gradient, λEm is measured at different concentrations of Hg at 350nm 2+ The fluorescence intensity of the solution was obtained as F0; 3) Mixing the sample to be tested with the ROR-CDs solution under the condition of pH=8.0 to obtain a mixed solution of the sample to be tested, and measuring the fluorescence intensity F of the mixed solution of the sample to be tested; 4) According to the fluorescence quenching efficiency F / F0 and Hg 2+ The linear relationship between the concentration and the Hg content in the sample to be tested is calculated. 2+ concentration; The linear relationship is obtained by obtaining the fluorescence quenching efficiency F / F0 and Hg 2+ Linear relationship with concentration.

6. The application according to claim 5, characterized in that: The fluorescence quenching efficiency F / F0 and Hg 2+ The linear relationship of concentration includes: In the range of 0-20 μg / L, the linear equation is y=0.97453-0.01565*x; R 2 =0.9926, LOD=19.16ng / L; In the range of 20-250 μg / L fluorescence, the linear equation is y=0.64582-0.00165*x; R 2 =0.9910, LOD=18.18ng / L.

7. The use according to claim 4, characterized in that: The ROR-CDs are used as fluorescent probes to quickly detect the content of chlortetracycline hydrochloride CTC.

8. The application according to claim 7, characterized in that: The step of detecting chlortetracycline hydrochloride by ROR-CDs comprises: 1) Dissolving the oil residue carbon dots in water to obtain ROR-CDs solution; 2) Mix the chlortetracycline hydrochloride CTC to be detected with 10 μL ROR-CDs solution, add different volumes of 1 mM CTC solution, and dilute to 1.0 mL with pH=12 phosphate buffer solution to form a CTC concentration gradient. Measure the fluorescence intensity of CTC solutions of different concentrations at λEm of 350 nm to obtain F0; 3) Mixing the sample to be tested with the ROR-CDs solution under the condition of pH=12.0 to obtain a mixed solution of the sample to be tested, and measuring the fluorescence intensity F of the mixed solution of the sample to be tested; 4) Calculate the concentration of CTC in the sample to be tested based on the linear relationship between the fluorescence quenching efficiency F / F0 and the CTC concentration.

9. The application according to claim 8, characterized in that: The linear relationship between fluorescence quenching efficiency F / F0 and CTC concentration is used to calculate the concentration of CTC in the sample to be tested, including: When the fluorescence linear range is 0-5 μM, the linear equation is y=0.19174+0.23463*x; R 2 =0.9938; detection limit is 12.7nM (S / N=3); When the fluorescence linear range is 5-50 μM, the linear equation is y=0.96032+0.08678*x; R 2 =0.9939; detection limit is 34.57nM (S / N=3).

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